JPS5935007A - Purification of selenium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention generally relates to a method for producing selenium, and more specifically, the present invention relates to an improved method for producing high-purity selenium by subjecting selenium esters to a reduction reaction. It is. In one important embodiment of the invention, high purity, Part 99.999 selenium, selenite, selenium oxide or mixtures thereof are reacted with alcohol, followed by reaction.

It is produced by separating the generated selenium ester and subjecting it to a reduction reaction. Selenium produced in this manner includes one, for example, the photoconductive imaging component of a xerographic imaging device. It can be used in some applications requiring high purity materials. Additionally, the high purity selenium produced according to the method of the present invention can be alloyed with other elements such as arsenic, tellurium, thallium, antimony, bismuth, etc., and the alloys can be incorporated into xerographic imaging components. can do.

The incorporation of selenium or selenium alloys into xerographic imaging components is well known in the art.

In order to sensitize the surface of the photoconductive layer, a uniform electrostatic charge is applied to these components and the primary irradiation is performed with a beam of light that selectively dissipates the charge on the surface of the photoconductive insulating component. The image can be exposed to active electromagnetic radiation to create an electrostatic latent image in an unilluminated field. The image can be developed and made visible by depositing toner particles onto the resulting image.

M゛Near, amorphous selenium, trigonal selenium, amorphous selenium/
-7fz Contains gold, halogen-dosed selenium, halogen-dosed selenium alloy, phthalocyanine, etc. Photoresponsive devices with layers of organic and inorganic materials have been developed. Such a photoresponsive component consists of a 1%''ll substrate, a photogenerating layer containing vanadyl phthalocyanine or trigonal selenium, and a transport layer containing a diamine dispersed in a resinous binder. 9 See, eg, US Pat. No. 4,265,990 it.

The selenium or selenium-containing alloy selected for the photoconductive imaging component is of high purity, -f i.e. 99.9991
or higher purity, since the presence of impurities in the microorganism may adversely affect the performance of the photoconductive component, including its electrical properties, and such devices cannot be used. This is because the image quality of copies made with high-purity selenium is relatively poor compared to equipment using high-purity selenium. Although methods are now available to produce day-purity selenium.

These methods involve several chemical and physical steps and generally high temperature distillation. Therefore, prior art methods for producing high purity selenium and selenium alloys are complex, economically unattractive, and cause environmental pollution. Such processes also produce volatile oxides, such as during high-temperature distillation, mercury must be removed in special additional steps, and chemical reagents used in the process are often recycled. It can be dangerous to an individual's health in that it is impossible to do so. Moreover, prior art methods can yield selenium products with different electrical properties despite adhering to identical processing conditions.

Current common industrial methods used to produce high-purity selenium include selenite from crude selenium;
Complex repetition of H2SeO3 production followed by purification and ion exchange steps? Contains.

The selenium precipitate was further purified and melted, and about 600
Distillation is carried out at relatively high temperatures ranging from 0.degree. C. to 700.degree. C., followed by vacuum distillation. Distillation requires extremely primitive and expensive equipment, and as pointed out earlier,
All contaminating products such as vaporous oxides and mercury must be safely removed. Also, this prior art method involves several complex steps and all of the undesirable waste produced must be disposed of.

U.S. Pat. No. 4,007,255 and 4.0
No. 09,249 discloses the production of stable red amorphous selenium containing thallium and the production of red amorphous selenium. U.S. Pat. No. 4,007,255 teaches about 10 ppm to about 'IO+000 ppm.
selenite containing thallium dioxide at f, about 5
From a solution in methanol or ethanol containing no more than 0 weight percent of water at a temperature between about -20°C and the freezing point of the solution.

The process consists of precipitating with hydrazine and maintaining the resulting precipitate at a temperature of about -16'C to about -6°C until the ha turns red in color. A method for producing an amorphous blue-coloured selenium material containing thallium is disclosed. US Pat. No. 4,009,249 contains a similar disclosure, except that it does not contain thallium in the material being treated.

In addition to the above methods for producing selenium.

Several other methods of producing selenium and selenium alloys are known. For example, U.S. Pat. No. 4,121,981
The patent discloses an electrochemical method for producing a photoreceptor comprising a selenium-tellurium layer. More specifically,
In this patent specification old F.

Selenium and tellurium are deposited on the substrate from a bath solution of these ions in a manner that controls the relative concentrations of selenium and tellurium in the electrolyte and the relative tY of selenium and tellurium deposited by selection of electrochemical conditions. The formation of a light-emitting layer by electrochemical co-deposition is disclosed.

Therefore, there is a need for improved methods of producing high purity selenium. Additionally, there continues to be a need for a simple, low temperature chemical modification process for producing high purity selenium and selenium alloys. In addition, it contains the least number of processing steps, does not require repeated ion exchange treatments or high-temperature distillation from 600°C to 700°C, and most of the chemical reagents can be recycled and can be used again. However, there also continues to be a need for improved methods of producing high purity selenium. Moreover, it reduces environmental hazards associated with the production and removal of hazardous substances. There also continues to be a need for improved processes for the production of serefun in high yields. There also continues to be a need for improved methods of producing high purity selenium with consistent electrical properties.

It is an object of the present invention to provide a method for producing high purity selenium which overcomes the above-mentioned disadvantages.

It is another object of the present invention to provide an improved method for producing high purity selenium by IMfing the pure selenium ester VcM base reaction.

Yet another object of the present invention is to provide an improved process for producing relatively high yield, high purity selenium.

An additional object of the present invention is that most of the reactants can be recycled. The purpose of the present invention is to provide a simple low-temperature method to purify selenium.

Yet another object of the invention is to treat crude selenium with a strong acid to produce oxidized ? +'& then react with alcohol and then purify the separated ester Z by e.g. distillation or crystallization and then perform low temperature reduction reaction, using 115"C or lower temperature to achieve high yields. This article provides a method for manufacturing pure selenium.

Yet another object of the invention is to provide an improved method for producing high purity selenium that is essentially free of pollutant emissions and does not require complex and expensive high temperature distillation equipment such as quartz. .

It is a further object of the present invention to provide an improved method of producing pure selenium with consistent and improved electrical properties.

These and other objects of the invention selenite.

It consists of reacting selenium oxide or a mixture thereof with alcohol, and then separating the resulting selenium ester and subjecting it to a reduction reaction χ. This is achieved by providing an improved method for producing high purity selenium. In a modification of the method of the present invention, crude selenium is reacted with a strong acid such as arsenic acid, sulfuric acid or a mixture thereof to produce selenite,
A mixture of selenium oxide and garlic is produced. Such processes are economical, especially since they involve only a few processing steps, do not require high-temperature distillation and expensive equipment, and most of the treated material can be recycled for use in the process. has a charm.

The method of the invention will now be briefly described with reference to the following representative preferred embodiments, however, the processing conditions.

Parameters and reactants other than those specified may be selected for the process of the present invention as long as the purpose thereof is achieved.Therefore, there is no intention to limit the process to the reactants and processing conditions described below.

In an important embodiment of the present invention, selenite is reacted with an aliphatic alcohol to form a liquid dialkyl selenite of the formula (RO)2SeO, where I-R is defined herein as an alkyl group. Purity to produce ester is 99,999
An improved method for producing % ya' of selenium is provided. The selenite is separated from the reaction mixture, further purified by distillation, and subjected to a reduction reaction to produce high-yield, high-purity selenium.

In a variation of the method of the invention, crude selenium is added to nitric acid.

Dissolved in strong acids such as sulfuric acid and mixtures thereof.

Produce selenite, selenium oxide and mixtures thereof.

The aliphatic alcohol selected for the process of the invention is generally 2ROH, where R has from 1 to about 6 carbon atoms.
Alkyl groups containing up to 0, preferably 1 to about 6 carbon atoms. Representative examples of preferred R groups for aliphatic alcohols and selenites include methyl, ethyl, propyl, butyl, pentyl and hexyl.

Methyl and ethyl are preferred. Particularly preferred alcohols selected for the process of the invention include methanol, ethanol and propatool.

In another important variation of the process of the invention, a diol can be used instead of an aliphatic alcohol for the formation of the ester. The diol of choice generally has the formula HO(CR
R2)nOH, where R and R2 are hydrogen or an alkyl group as defined herein, and n is a number ranging from 1 to about 10. Examples of preferred diols that may be selected include ethylene glycol and zoropylene glycol.

The selenium ester produced in the diol reaction has the general formula 0
In the formula, R3 is ethylene or methinon. It is an alkylene group such as zorogylene.

In one exemplary embodiment of the method of the present invention, Fisher Scientific Company (Fisher Scientific Co., Ltd.)
Crude selenium material, which can be purchased from 5 Scientific Company, is oxidized to the corresponding oxide by dissolving it in a strong acid such as nitric acid. As the strong acid, industrially available concentrated nitric acid, industrially available concentrated sulfuric acid, and a mixture thereof +wJ are selected for the method of the present invention. If a mixture of acids is used, generally from about 20% sulfuric acid and about 80% nitric acid are used, but mixture percentages can range from about 5% sulfuric acid to about 95% nitric acid, with about 10% sulfuric acid being used. % to nitric acid about 90%
% is preferred. A preferred acid is nitric acid, mainly because it has strong oxidizing power against selenium. Other chemical reagents such as hydrogen peroxide, monomolecular oxygen, etc. can also be used to effect this conversion. In general, crude substances have a purity of about 98%, including arsenic, bismuth, etc.
cadmium, chromium.

Iron, sodium, magnesium, lead, antimony.

Tin, silicon, titanium, nickel, lead, thallium.

It contains several impurities such as boron, barium, mercury, zinc, other metal and non-metal impurities, etc.

The amount of crude selenium to be dissolved can be varied based on, for example, the amount of high purity product desired. Typically, from about 1 pound to about 165 pounds of crude selenium is dissolved, preferably from about 1 pound to about 500 grams, but it is understood that any amount of crude selenium can be dissolved if desired. It should be recognized.

Generally, the acid used to dissolve the crude selenium product ranges from about 60 ON to about 1
200 d, preferably about 800 ba to about 9 q
An amount of Q ntl is added to this. The resulting suspension of selenium and acid is stirred at a temperature sufficient to completely dissolve the crude selenium in VC.

In certain embodiments, the suspension is heated at a temperature between about 65° C. and about 85° C. for a time sufficient to completely dissolve the crude selenium, as observed in the production of a clear solution. Stir continuously. This solution usually forms from about 1 hour to about 6 hours, but 1 hour can vary significantly depending on the chosen step, ie.

For example, if you stir very vigorously at high temperatures.

Completely dissolves the crude selenium within about 1 hour or less, whereas slow stirring at low temperatures below 60°C
The crude selenium cannot be dissolved until about 6 hours or more.

The concentrated acid mixture is then separated from the resulting clear solution at a suitable temperature, e.g. 110 DEG C. in the case of separating nitric acid, by several known methods including distillation.

The resulting separated acid is collected in a suitable container, such as a distillation vessel, and then the crude selenium product 'Jf! Recirculate and use repeatedly to dissolve IJ.

After the distillation reaction and separation of the acid from the solution mixture, a white powder identified as selenite, H2SeO3, and other selenium oxides such as selenium dioxide are obtained. next,
9 where R is an alkyl group containing from 1 to about 60 carbon atoms, preferably from about 1 to about 6 carbon atoms;
An aliphatic alcohol or diol with the formula ROH is added to this powder.

Produces liquid selenium ester. Generally, about 500 In! for conversion to selenium esters. Up to about 600 molar to about 700 molar aliphatic alcohols or diols are used, but other suitable amounts of alcohols may be selected.

The water formed after addition of the aliphatic alcohol or diol can optionally be removed by an azeotropic distillation process. This is done by boiling the mixture with various azeotropes such as aliphatic and aromatic hydrocarbons including toluene, benzene and pentane. Known azeotropic distillation processes can be carried out at temperatures at which the entrainer begins to boil; thus, when using pentane, this temperature ranges from about 60°C to about 35°C. Because it does not adversely affect the purity of the selenium product obtained.

Although it is not necessary to azeotropically remove water from the reaction mixture, it is preferred in the process of the present invention to obtain even higher yields of product, for example.

Complete removal of water and therefore complete conversion to selenium esters is generally achieved in a period of from about 8 hours to about 10 hours.

Excess aliphatic alcohol and hydrocarbon, if any, selected for azeotropic distillation are added to the resulting reaction mixture at a temperature of from about 70°C to about 80'O.

It is generally removed by distillation in a vacuum of about 5 columns of mercury. Next, if ethanol was used, it was identified by 1 spectroscopic analysis. Pure colorless liquid selenium ester, diethyl selenite, (C2H5)2SeO.

However, other dialkyl selenite esters can also be prepared with different alcohols.

The isolated pure selenite dialkyl ester can then be directly reduced to pure selenium in a reduction reaction, or as an optional step before reduction, water or an organic solvent such as cellosolve, ethanol, etc. By dissolving the pure ester into the pure selenium ester, about 25% to about 60%! in.

Preferably a solution containing from about 40% to about 50% is obtained.

The reduction reaction can be carried out at a variety of suitable temperatures, depending on, for example, the reducing agent selected and the solvent system used.

Generally, the reduction reaction is carried out at relatively low temperatures not exceeding about 1 oo'aya. In particular, the reduction reaction temperature can range from about 25° C. to about 100° C., depending on the reducing agent used, for example. Typical examples of reducing agents include hydrazine, sulfur dioxide, hydroxylamine, and hydroquinone.

Includes those well known in the art such as thiourea, glyoxal, ascorbic acid, pyrrole, phosphate, phosphite, and the like. Preferred reducing agents are hydrazine and sulfur dioxide.

The amount of reducing agent required depends on several factors such as chemical composition, Method 1 reaction temperature, concentrations of reactants used, etc. Usually, hydrazine is added for 1 hour until the reduction reaction is completed.
Although equimolar amounts are added, the sulfur-ganioxide is generally bubbled into the aqueous solution of the selenite dialkyl ester for a period of time sufficient to completely precipitate the selenium. Generally, the effervescence lasts from about 1 hour to about 5 hours, preferably from about 2 hours to about 3 hours, but outside this range provided that the objectives of the invention are achieved. You can choose the time.

Immediately upon completion of the reduction reaction, selenium precipitates of a certain color occur, and the specific color produced varies depending on the reducing agent selected and the reaction temperature. That is, when hydrazine is used as a reducing agent, a black precipitate of crystalline selenium is produced, but on the other hand, when sulfur dioxide is selected as the reducing agent,
A red precipitate of amorphous selenium forms. In addition, the desired high purity selenium can be separated from one reaction mixture by any suitable known method, including eight steps. continue.

An optional treatment step is washing with a suitable solvent such as separated selenium water or cellosolve;
The selenium can then be dried in air. Typically, about 500 me or more of cleaning solvent is selected per pound of precipitated selenium.

The purity of selenium produced according to the method of the invention was determined by emission spectroscopy, while the identity and purity of selenium esters were determined by infrared, nuclear magnetic resonance (NMR).

Measured by ultraviolet (UV'), mass spectrometry, and elemental analysis for carbon, oxygen, and hydrogen. The results obtained with the method of the invention are shown in Table 1 below.

Purity is determined by emission spectroscopy.

8 The value of the report is in units of 100 units, and 1 meter is 500 units of 100 units.
(ppm) or more of impurities.

(•) indicates that the specified element was not detected by emission spectroscopy. The term "residue" means the remainder in units of 100 parts of the composition contained in selenium. Furthermore, impurities silicon (Si) and magnesium (Mg
) and calcium (Ca ) &'j - believed to originate primarily from the glassware and funnels chosen and equipped for the process described.

Letter symbols A, B, C, D, and E indicate that the following sources have been selected for processing.

A - Industrial crude selenium B - Regenerated selenium (hydrazine reduction) C - Regenerated selenium (sulfur dioxide reduction) E - Industrial grade selenium dioxide (hydrazine reduction) E - Industrial grade selenite (hydrazine reduction) Furthermore, hydrazine as a reducing agent If you select .

Trigonal selenium is more commonly produced than amorphous selenium.

Such trigonal selenium has a purity of 99.9991.

According to the process of the invention, selenium products are also produced in high yields, i.e. from about 85% to 95%, usually from about 90% to 90%.
Yields ranging up to 5% are obtained. Therefore. Not only is the selenium product obtained in exceptional purity, i.e., 99.999%, extremely useful as the electrostatic imaging component of xerographic imaging devices, but such raw materials are available in high yields. The results obtained make the process of the invention economically attractive and highly practical.

High purity selenium produced according to the method of the invention can be used as the imaging component of xerographic imaging devices. Such components are generally referred to as inorganic photoresponsive devices or layered organic photoresponsive devices. As an inorganic photoresponsive device.

Selenium was deposited on the prepared aluminum substrate.

The resulting component is subjected to a uniform electrostatic charge, and the resulting sensitized surface is then exposed to electromagnetic radiation, such as a beam of light, into an image pattern. When the device is exposed to a beam of light, the initially applied charge is selectively dissipated, producing a positive electrostatic image sound, which is then converted into components of oppositely charged toner particles according to known methods. Coat and develop. The developed image is then transferred to a suitable substrate such as 9 paper.

This can be permanently fixed.

An example of a layered organic photoresponsive device containing high purity selenium prepared according to the method of the present invention is disclosed in U.S. Pat. No. 4,265, herein incorporated by reference.
The present invention includes a device comprising generation and transport layers as described in the '990 specification.

Examples of generator layers for such devices include trigonal selenium, while examples of transport layers disclosed in this patent include various diamines dispersed in an active resinous binder mixture. ing.

Although the following example describes nine preferred embodiments of the invention, this example is not intended to limit the scope of the invention, and various other parameters not mentioned in % are within the scope of the invention. I would like to point out that it is included. Parts and percentages are by weight unless otherwise indicated. Selected selenium source materials include crude selenium, technical grade selenite, and selenium dioxide. The purity of regenerated selenium was determined by emission spectroscopy.

Example 1 In this example, crude selenium was first treated with nitric acid, converted to selenite, and then subjected to a condensation reaction with an alcohol using infrared rays and nuclear magnetic resonance (NMR).

Identification was made by mass spectroscopy and elemental analysis for hydrogen, oxygen and carbon. A dialkyl selenite is obtained. The production of diethylselenide from crude selenium source material is described.

One pound of crude selenium powder was dissolved in concentrated nitric acid by stirring and warming in a round bottom (RB) flask for 3 hours.
I understood VC#. After making the melt g
The nitric acid is removed by distillation at temperatures up to 12°C and remains in the primary stage. Traces of nitric acid were removed under high vacuum. The resulting white residue was dissolved in 7QQm of absolute ethanol, and all the water formed was removed azeotropically with a benzene 600 column. The azeotropic distillation was completed in about 15 hours. Benzene and excess ethanol were then removed by vacuum distillation at normal pressure, and the resulting residue was fractionally distilled under high vacuum. Pure diethyl selenite boiling at 65°C/3 mm was collected. The gray residue left in the flask was dissolved in anhydrous ethanol (800 In
and benzene/(600m). All of the resulting water was removed by azeotropic distillation to obtain an additional yield of diethyl selenite. The overall yield of diethyl selenite was 90% (95
6g). This yield can be increased by recycling the gray residue left in the flask.

Example 2 This example describes the reduction of pure diethyl selenite prepared according to Example 1 with sulfur dioxide in an aqueous medium.

21 Erlenmeyer
Sulfur dioxide gas was gently bubbled into a solution of 400 g of diethyl selenite prepared according to Example 1 in 1,000 ml of deionized water in a flask for 2 hours at room temperature. A red precipitate of amorphous selenium began to separate from the solution. The faintly formed red precipitate was collected and washed several times with water until the washing water was neutral (P)l = 7). The precipitate was slightly dried under vacuum and its weight was measured. Total yield 1
10 g (65%) of red amorphous selenium was obtained. This income #
C.1 can be improved by raising the reaction temperature and bubbling out sulfur dioxide for a sufficient time to dissipate the red color in the f-liquid.

In emission spectroscopy, the selenium produced was slightly less pollutant.

Fe 1 ppm, Mg 5 ppm, and Si
The selenium content was only 5 ppm, indicating that the purity of the produced selenium was 99.999%.

Example 6 This example illustrates the reduction of diethyl selenite prepared according to the method of Shiefu Example 1 with hydrazine in an organic medium.

Diethyl selenite (400,1il) Y cellosolve (
The solution was charged to a 6130 round bottom (RB) flask equipped with a draft condenser, graduated addition funnel, and a Teflon® paddle-shaped stirrer. Cellosolve 100mt and hydrazine 85.
? tzr: mg selenite ester w in addition funnel with stirring.

Dropped into this. This dropping took about 1 hour.

The resulting black precipitate was collected by passing through a sintered glass filter, washed with 200 ml of Cellosolve (4×50 ml), dried, and the heavy liquid was measured.

169 g of selenium (yield 99%) was obtained. In emission spectroscopy, raw 1j! ZL, selenium has slightly less contaminants.

/'J-1pT)m, Calppm, CuO
, 2 ppm, Fo 2 ppm.

There are only 10 ppm of Mg and 10 ppm of Si, and the purity of the selenium produced is 99.999.

Example 4 In this example, industrial grade selenite (section 94) was used. I
p, to explain the conversion to dienal selenate.

Selenite (100&), anhydrous ethanol (2001A
A mixture of f) and benzy (200 ml) was mixed with Dean
A 11 round bottom flask was equipped with a Dean-8 Stark reflux column.

The mixture was stirred in an argon atmosphere with a certain amount of gamma width until the solution was completely dissolved. The reaction mixture was gently refluxed and water was removed azeotropically. It took approximately 7 hours to complete the reaction to this point.

Excess ethanol and benzene were removed by distillation.

The resulting gray residue was distilled under reduced pressure. ,68'C
A colorless liquid that distills at a j/5 mrtt89. V was collected.

The gray solid residue was redissolved in a mixture of ethanol (100ml) and benzene (150ml).

After azeotropic stripping to remove excess ethanol and benzene, the residue was fractionally distilled. A fraction of 68"C15 was collected and identified as pure diethyl selenite using infrared rays and nuclear magnetic resonance (NMR), and carbon, oxygen, and hydrogen were confirmed by elemental system analysis. Since the amount of this fraction was 33 g, the total yield of diethyl selenite increased to 122.9 (91%).

Example 5 This example describes the reduction of diethyl selenite prepared from technical grade selenite with hydrazine dissolved in an organic medium.

A solution in which 122 g of diethyl selenite produced according to Example 4 was dissolved in 500 ml of cellosolve was described in Example B. 50 grams of cellosolve and 15 grams of hydrazine
Reduced with a solution containing +πt.

High purity (99,999%) selenium 51.5. ! 9 was produced. Emission spectroscopy revealed that the produced celery contained the following contaminants.

u 2ppm, Ca 1ppm, CuO,
2 ppm, Fe 2 ppm.

There were only 3 ppm of Mg and 7 ppm of Si, indicating that the purity of the selenium produced was 99.999%.

Example 6 This example describes the conversion of selenium dioxide to diethyl selenite.

Selenium dioxide (50g), p-)luenesulfonic acid (5
A mixture of g) in 500 WL of methanol was charged into a 11 round bottom flask equipped with a Dean-Stark apparatus. The reaction mixture was brought to reflux and heated with a S gas stirrer for 5 minutes.
Stir for an hour and obtain a clear solution during this time. Chloroform (200 m/s) was added to the reaction flask and water was removed azeotropically. Excess methanol and chloroform were distilled off and the residue in the flask was distilled under high vacuum. Pure dimethyl selenite was identified by infrared, nuclear magnetic resonance (NMR), mass spectroscopy and elemental analysis for carbon, hydroxyl and oxygen, and purified at 46°C/5 mm.
It was collected by distillation with mercury. Total yield of this ester 60g
(85%) were collected.

Example 7 Dimethyl selenite 156y produced according to Example B
A solution prepared by dissolving Cellosolve 5QQm was charged into 11 Erlenmeyer flasks. The mixture was stirred for 2 minutes with a magnetic stirrer at low temperature.

Next, while stirring the above reaction mixture, a solution of 20ml of hydrazine dissolved in 50ml of cellosolve was added dropwise. The dropping process took about 1 hour. The reaction was exothermic and N2 gas was generated. The resulting black precipitate was collected by filtration, washed and dried as described in Example B. A total of 759 (95%) crystalline selenium were collected.

According to emission spectroscopy, the selenium produced is one of the pollutants listed below.

Al2ppm, Ca1ppm, CuO,
2 ppm, Fe 2 ppm.

It contains only 3 ppm of Mg and 7 ppm of Si, and the purity of the selenium produced is 99.99.
7 showed that it was 9%.

Example 8 A high purity selenium product prepared according to the method in Examples 1 to 7-1 was deposited on an aluminum substrate from about 60%
00μ, and about 50μ to about 60μ on top of selenium.
It was deposited to a thickness of up to μ.

These imaging devices were incorporated as photoconductive imaging components into xerographic imaging devices to obtain high quality images with excellent resolution after development.

A process diagram for an embodiment of the method of the invention is shown in FIG. 1, in which crude selenium is treated with nitric acid,
Produce a mixed solution of selenium oxide. Excess nitric acid is then removed by distillation to obtain a selenium oxide powder mixture. Alcohol, ROH, was added to this powder mixture and 9
The water is then azeotropically removed. Pure selenium ester is produced after distillation. Next, this selenium ester is subjected to a reduction reaction using, for example, hydrazine or sulfur dioxide.

A selenium product with high purity of 99.999% as determined by emission spectroscopy is obtained. Alternatively, crude selenium dioxide, which is available commercially, or selenium acid, which is also available commercially.

Pure selenium esters can be produced by reacting H2SeO3 with an alcohol, ROH, with azeotropic removal of water. The identity and purity of the selenium esters were determined by infrared analysis, nuclear magnetic resonance (NMR), mass spectroscopy, and ultraviolet light, and carbon, hydrogen, and oxygen were determined by elemental analysis.

Nine other modifications of the present invention will occur to those skilled in the art based on the description of the present disclosure.

These modifications are intended to be included within the scope of this invention.

[Brief explanation of drawings]

FIG. 2 is a process flow diagram of an embodiment of the method of the present invention in the drawings. Agent Asamura Hao F/G/ 50-

Claims (1)

[Claims] fi+ The method is characterized in that selenite, selenium oxide, or a mixture thereof is reacted with alcohol, the resulting selenium ester is purified, and then subjected to a reduction reaction. A method for producing high purity selenium. (2) Alcohol has the formula ROH, and in the 5 formulas, R&
A method according to paragraph fi1 above, characterized in that X is an alkyl group containing from 1 carbon atom to about 6 carbon atoms. (3) The method according to item (2) above, wherein the alcohol is methanol or ethanol. (4) The method according to item (1), wherein selenite, selenium oxide, or a mixture thereof is produced by reacting crude selenium with a strong acid. (5) The acid is nitric acid.
The method described in section 4). (6) The selenium ester produced has the formula (RO)zseo
and wherein Rkj is an alkyl group containing from 1 carbon atom to about 6 carbon atoms. (7) The method according to item (6) above, wherein R is methyl or ethyl. (8) Hydrazine, sulfur dioxide, and thiourea as reducing agents. The method according to item (1) above, characterized in that hydroxylamine, hydrochloride, or ehydrazine hydrochloride is selected. (9) The method according to item (1), characterized in that selenium is produced with a purity of 99.999%. The method according to paragraph 1. αυ The method according to paragraph 1, characterized in that the reduction reaction is carried out at a temperature from about 25°C to about 80°C. a'a Sevanous acid, selenium oxide Also km these m
& things to R1 and R2 in the 2HO<CRIB2)nOH C formula! An alkyl group containing from 1 to 60 carbon atoms. and D is a number from about 1 to about 10) The selenium ester produced is separated and purified, and then subjected to a reduction reaction. A method for producing high purity selenium. tl(] The formula of the selenium ester produced is C formula, R
To 3'! The method according to item (14), wherein the diol is ethylene glycol or zoropylene glycol.
The method described in section.